Examples of Arthropod Vectors
Phlebotmine SandflyCulex Mosquito
Assorted TicksAedes Aegypti
• The biggest arbovirus problem in the world
today with over 2 million cases per year
• Dengue is found in SE Asia, Africa and S
• Transmitted by Aedes mosquitoes residing in
• Transmission cycle: human-mosquitoe-human
• High fever, lymphadenopathy, myalgia, bone
and joint pains, headache, and a
• Severe cases may present with haemorrhagic
fever and shock with a mortality of 5-10%.
(Dengue haemorrhagic fever or Dengue shock
• Diagnosis : by serology.
• Treatment: no specific antiviral
Removal of all containers from premises
which may serve as vessels for egg
A live attenuated vaccine is being tried in
Thailand with encouraging results.
• Rabies is a zoonosis which is prevalent in
• The animals involved differ from
continent to continent.
• Wide range of hosts: fox, bats wolf dog
and harbor the
virus in saliva
Rabies: Clinical Features
• Incubation Period depends on:
Site of animal bite
• Prodromal Period (up to two weeks)
Pain or itching at the site of the wound,
Fever & headache.
• CNS infection (Neurological phase)
Hydrophobia in half of the patients.
Seizures and hallucinations.
Paralysis leading to respiratory failure
Coma & death
• Are pathognomonic of rabies
• Are intracytoplasmic inclusions
formed by aggregates of
nucleocapsids in neurons of
about 90% of infected humans
Negri Body in neuron cell
Management and Prevention
• Inactivated rabies vaccine to high risk persons like vets,
animal handlers, laboratory workers etc.
• In cases of animal bites, dogs and cats in a rabies endemic
area should be held for 10 days for observation. If signs
develop, they should be killed and their tissue examined.
• Local treatment of wounds
• Passive immunization - human rabies immunoglobulin
• Active immunization - the human diploid cell vaccine is
usually administered into the deltoid region, and 5 doses are
• Nothing much can be done except
intensive supportive care.
• To date, only 2 persons with proven
rabies have survived.
Management and Prevention
Control of Rabies
• Urban - canine rabies: 99% of
all human rabies.
– Dog control
– Vaccination of dogs
– Quarantine of imported animals
• Wildlife - much more difficult
• G Protein (Surface glycoprotein)
– Binds to cellular receptors and is the target of
• M (matrix) protein.
– This is a peripheral membrane protein may act as
a bridge between the membrane or G protein and
• N (Nucleoprotein) protein
– This is the major structural protein that covers
the RNA genome and protects it from nucleases.
• L (Large) protein
– Its gene takes up 60% of the genome
• P (phospho)) protein
Rabies Virus Proteins